We report experimental and molecular simulation studies that confirm the presence of a hexatic phase in narrow pores. On heating, starting with a solid crystalline phase in the pore, two transitions are observed, the first being crystal to hexatic, and the second occurring at a higher temperature from hexatic phase to liquid. The molecular simulations are for large systems (64,000 molecules) and free energies are determined by the Landau free energy method. These clearly show the two transitions, and the nature of the confined phases are determined by measurement of the spatial and orientational correlation functions. Finite size scaling methods are used to show that these transitions persist in the large system limit. For the narrower pore width studied, only one layer of adsorbate molecules can be accommodated in the pore, and the transitions are second order. With a larger pore two adsorbed layers can be accommodated, and the transitions become first order. The results are consistent with the Kosterlitz-Thouless-Halperin-Nelson-Young theory for melting in two dimensions.
Experimental studies are reported for carbon tetrachloride and aniline adsorbed in activated carbon fibers having slit-shaped pores. Differential scanning calorimetry, dielectric relaxation spectroscopy and nonlinear dielectric effect measurements were made. The measurements show two transitions at temperatures that are in good agreement with those found in the simulations for the crystal/hexatic and hexatic/liquid transitions for both carbon tetrachloride and aniline in activated carbon fibers. Recently a similar effect was found for benzene in ACF.
In conclusion, we find that (a) a hexatic phase can occur in narrow pores, (b) the phase occurs even for simple molecules, and is stabilized by the confinement of the pore; thus it occurs over much broader temperature ranges than has been observed in bulk fluids.

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